High glass transition temperature polycarbonates derived from adamantane epoxides

ABSTRACT

Embodiments in accordance with the present invention relate generally to polycarbonate polymers having repeat units derived from adamantane epoxide monomers and methods of using such polymers and compositions containing them. The compositions thus formed are useful in a variety of optoelectronic device fabrications.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/577,218 filed Oct. 26, 2017, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments in accordance with the present invention relate generally to polycarbonate polymers having repeat units derived from adamantane epoxide monomers and methods of using such polymers and compositions containing them.

BACKGROUND

Optically clear commercial poly(alkylene carbonate) binder materials, such as poly(ethylene carbonate) (PEC) and poly(propylene carbonate) (PPC), have demonstrated utility in air-gap formation for electrical/optical interconnects, microelectromechanical systems (MEMS) device fabrication, microfluidics, and micro-reactor applications because of their photoimageability in the presence of a photoactive additive. For example, Unity® 2203P, which contains a poly(alkylene carbonate), can be patterned by UV exposure (typically at 365 nm) in the presence of a suitable additive. However, retention of pattern fidelity and feature resolution is limited due to polymer flow issues (e.g., rounded features, slanting side walls) in post-exposure development. These thermal flow properties are attributed to the low glass transition temperature (T_(g), 40° C.) of the base polymer (PPC) which is significantly lower than the development temperature. Thus, there is a need to develop new photoimageable polymers which are formed from readily available monomers and exhibit the following properties: (i) high T_(g) (T_(g)≥120° C.), (ii) soluble in common process solvents, (iii) have sufficient M_(w) (at least 5,000) to attain formulation viscosity required for thin film generation by spin or spray coating and have mechanical strength, (iv) decompose cleanly at low temperatures (<200° C.) in the presence of a photoactive additive, and (v) leave essentially no residue after post-exposure thermal development. The low residue requirement is important in cases where cleaning is not possible, e.g., encapsulated microchannels generated from decomposition of sacrificial materials covered by an overcoat.

U.S. Pat. No. 6,743,570 B2 ('570 patent) discloses a method of using heat-depolymerizable polycarbonate, such as poly(cyclohexene carbonate) to create a nano-fluidic device. In this method, areas of polycarbonate exposed to e-beam were removed by immersion in isopropanol, with optional plasma cleaning in a UV-ozone cleaner. In a later part of the device fabrication, after depositing a capping layer, the underlying heat-depolymerizable polycarbonate was removed by baking at temperatures above 300° C. for 30 min or longer. No photoactive component was mentioned in the disclosure. The poly(cyclohexene carbonate) was prepared from alternating copolymerization of cyclohexene oxide with carbon dioxide using (BDI)ZnOR (R=Ac, Me) catalysts in accordance with the procedures described by Cheng et al., J. Am. Chem. Soc. 1998, 120, 11018-11019; also see J. Am. Chem. Soc. 2003, 125, 11911-11924. Various other catalyst systems have also been used for the preparation of polycarbonates by alternating copolymerization of epoxide with carbon dioxide, see Catal. Sci. Technol. 2012, 2, 2169-2187 and references cited therein.

It should be noted that the post e-beam immersion in isopropanol processing as disclosed in '570 patent may not be suitable in many applications where the polycarbonate is intended for removal after an overmolding step, such as in a typical semiconductor fabrication. Furthermore, the alternative harsh baking conditions (higher than 300° C. for a period in excess of 30 minutes) may not be compatible with expected throughput and thermally sensitive components in a semiconductor device.

U.S. Pat. No. 6,586,154 B1 ('154 patent) discloses a series of photoresist polymer compositions which are polycarbonates derived from various polycyclic diols and carbon dioxide. It should be noted that the disclosures of '154 patent appear to require a wet development step after a post-exposure bake, as disclosed therein several of the examples included a 40-second tetramethylammonium hydroxide (TMAH) development step.

U. S. Patent Application Publication No. 2004/0132855 discloses a series of photodefinable polymers, which include polynorbornenes, polycarbonates, polyethers and polyesters. As disclosed therein, residues formed from certain decomposable materials, such as polyimide, polynorbornene, and polycarbonate are removed by plasma reactive ion etch (RIE). This aspect of the process may not be suitable in cases where the microchannel is encapsulated by an overcoat.

Accordingly, there is still a need for developing polymer compositions that can be dry developed with essentially no residue left behind.

Other objects and further scope of the applicability of the present invention will become apparent from the detailed description that follows.

SUMMARY OF THE INVENTION

Surprisingly, it has now been found that polycarbonates derived from adamantane epoxide exhibit one of the highest glass transition temperature (T_(g)) that can be attained by any of the polycarbonates known thus far, and therefore, provide a new class of high temperature polycarbonates having potentially improved pattern fidelity by reducing polymer flow issues typically encountered during post-exposure thermal development. The polycarbonate embodiments with adamantane epoxides are generated by alternating copolymerization of carbon dioxide and the corresponding adamantane epoxide using a ligand-supported metal catalyst (e.g., cobalt, and zinc).

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments in accordance with the present invention are described below with reference to the following accompanying figures and/or images. Where drawings are provided, it will be drawings which are simplified portions of a device provided for illustrative purposes only.

FIG. 1 shows a differential scanning calorimeter (DSC) thermogram of a polymer embodiment in accordance with the present invention, which is compared with DSC thermograms of a few of the known polycarbonates as Comparative Examples as described herein.

DETAILED DESCRIPTION OF THE INVENTION

The terms as used herein have the following meanings:

As used herein, the articles “a,” “an,” and “the” include plural referents unless otherwise expressly and unequivocally limited to one referent.

Since all numbers, values and/or expressions referring to quantities of ingredients, reaction conditions, etc., used herein and in the claims appended hereto, are subject to the various uncertainties of measurement encountered in obtaining such values, unless otherwise indicated, all are to be understood as modified in all instances by the term “about.”

Where a numerical range is disclosed herein such range is continuous, inclusive of both the minimum and maximum values of the range as well as every value between such minimum and maximum values. Still further, where a range refers to integers, every integer between the minimum and maximum values of such range is included. In addition, where multiple ranges are provided to describe a feature or characteristic, such ranges can be combined. That is to say that, unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a stated range of from “1 to 10” should be considered to include any and all sub-ranges between the minimum value of 1 and the maximum value of 10. Exemplary sub-ranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, and 5.5 to 10, and so on so forth.

As used herein, “hydrocarbyl” refers to a moiety or a group that contains only carbon and hydrogen, non-limiting examples being alkyl, cycloalkyl, aryl, aralkyl, alkaryl, and alkenyl. The term “halohydrocarbyl” refers to a hydrocarbyl group where at least one hydrogen has been replaced by a halogen. The term perhalocarbyl refers to a hydrocarbyl group where all of the hydrogens have been replaced by a halogen.

As used herein, the expression “(C₁-C₆)alkyl” includes methyl and ethyl groups, and straight-chained or branched propyl, butyl, pentyl and hexyl groups. Particular alkyl groups are methyl, ethyl, n-propyl, isopropyl and tert-butyl. Derived expressions such as “(C₁-C₄)alkoxy”, “(C₁-C₄)thioalkyl” “(C₁-C₄)alkoxy(C₁-C₄)alkyl”, “hydroxy(C₁-C₄)alkyl”, “(C₁-C₄)alkylcarbonyl”, “(C₁-C₄)alkoxycarbonyl(C₁-C₄)alkyl”, “(C₁-C₄)alkoxycarbonyl”, “amino(C₁-C₄)alkyl”, “(C₁-C₄)alkylamino”, “(C₁-C₄)alkylcarbamoyl(C₁-C₄)alkyl”, “(C₁-C₄)dialkylcarbamoyl(C₁-C₄)alkyl” “mono- or di-(C₁-C₄)alkylamino(C₁-C₄)alkyl”, “amino(C₁-C₄)alkylcarbonyl” “diphenyl(C₁-C₄)alkyl”, “phenyl(C₁-C₄)alkyl”, “phenylcarboyl(C₁-C₄)alkyl” and “phenoxy(C₁-C₄)alkyl” are to be construed accordingly.

As used herein, the expression “cycloalkyl” includes all of the known cyclic groups, including polycyclic groups further defined below, such as bicycloalkyl, and so on. Representative examples of “cycloalkyl,” which are mono-cyclic groups, include without any limitation cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and the like. Derived expressions such as “cycloalkoxy”, “cycloalkylalkyl”, “cycloalkylaryl”, “cycloalkylcarbonyl” are to be construed accordingly.

As used herein, the expression “bicycloalkyl” includes all of the known bicyclic groups. Representative examples of “(C₆-C₁₂)bicycloalkyl” includes without any limitation bicyclo[2.1.1]hexane, bicyclo[2.2.1]heptane, bicyclo[[3.2.1]octane, bicyclo[2.2.2]octane, bicyclo[3.2.2]nonane, bicyclo[3.3.1]nonane, bicyclo[3.3.2]decane, bicyclo[4.3.1]decane, bicyclo[4.4.1]undecane, bicyclo[5.4.1]dodecane, and the like. Derived expressions such as “bicycloalkoxy”, “bicycloalkylalkyl”, “bicycloalkylaryl”, “bicycloalkylcarbonyl” are to be construed accordingly.

As used herein, the expression “tricycloalkyl” includes all of the known tricyclic groups. Representative examples of “(C₇-C₁₄)tricycloalkyl” includes without any limitation tricyclo[2.2.1.0^(2,6)]heptane, tricyclo[3.2.1.0^(2,4)]octane, tricyclo[4.2.1.0^(2,5)]nonane, octahydro-1H-4,7-methanoindene, octahydro-1H-4,7-ethanoindene, octahydro-1H-cyclopropa[a]pentalene, decahydrocyclopenta[cd]-pentalene, dodecahydro-1H-phenalene, adamantyl and the like. Derived expressions such as “tricycloalkoxy”, “tricycloalkylalkyl”, “tricycloalkylaryl”, “tricycloalkylcarbonyl” are to be construed accordingly.

As used herein, the expression “tetracycloalkyl” includes all of the known tetracyclic groups. Representative examples of “(C₁₀-C₁₄)tetracycloalkyl” includes without any limitation tetracyclo[3.2.2.2^(1,5).0^(2,4)]undecane, decahydro-1,4:5,8-dimethanonaphthalene and the like. Derived expressions such as “tetracycloalkoxy”, “tetracycloalkylalkyl”, “tetracycloalkylaryl”, “tetracycloalkylcarbonyl” are to be construed accordingly.

As used herein, the expression “(C₆-C₁₀)aryl” means substituted or unsubstituted phenyl or naphthyl. Specific examples of substituted phenyl or naphthyl include o-, p-, m-tolyl, 1,2-, 1,3-, 1,4-xylyl, 1-methylnaphthyl, 2-methylnaphthyl, etc. “Substituted phenyl” or “substituted naphthyl” also include any of the possible substituents as further defined herein or one known in the art. Derived expression, “(C₆-C₁₀)arylsulfonyl,” is to be construed accordingly.

As used herein, the expression “(C₆-C₁₀)aryl(C₁-C₄)alkyl” means that the (C₆-C₁₀)aryl as defined herein is further attached to (C₁-C₄)alkyl as defined herein. Representative examples include benzyl, phenylethyl, 2-phenylpropyl, 1-naphthylmethyl, 2-naphthylmethyl and the like.

As used herein, the expression “heteroaryl” includes all of the known heteroatom containing aromatic radicals. Representative 5-membered heteroaryl radicals include furanyl, thienyl or thiophenyl, pyrrolyl, isopyrrolyl, pyrazolyl, imidazolyl, oxazolyl, thiazolyl, isothiazolyl, and the like. Representative 6-membered heteroaryl radicals include pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, and the like radicals. Representative examples of bicyclic heteroaryl radicals include, benzofuranyl, benzothiophenyl, indolyl, quinolinyl, isoquinolinyl, cinnolyl, benzimidazolyl, indazolyl, pyridofuranyl, pyridothienyl, and the like radicals.

As used herein, the expression “heterocycle” includes all of the known reduced heteroatom containing cyclic radicals. Representative 5-membered heterocycle radicals include tetrahydrofuranyl, tetrahydrothiophenyl, pyrrolidinyl, 2-thiazolinyl, tetrahydrothiazolyl, tetrahydrooxazolyl, and the like. Representative 6-membered heterocycle radicals include piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, and the like. Various other heterocycle radicals include, without limitation, aziridinyl, azepanyl, diazepanyl, diazabicyclo[2.2.1]hept-2-yl, and triazocanyl, and the like.

“Halogen” or “halo” means chloro, fluoro, bromo, and iodo.

In a broad sense, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a few of the specific embodiments as disclosed herein, the term “substituted” means substituted with one or more substituents independently selected from the group consisting of (C₁-C₆)alkyl, (C₂-C₆)alkenyl, (C₁-C₆)perfluoroalkyl, phenyl, hydroxy, —CO₂H, an ester, an amide, (C₁-C₆)alkoxy, (C₁-C₆)thioalkyl, (C₁-C₆)perfluoroalkoxy, —NH₂, Cl, Br, I, F, —NH-lower alkyl, and —N(lower alkyl)₂. However, any of the other suitable substituents known to one skilled in the art can also be used in these embodiments.

As used herein, the symbol “

” denotes a position at which the bonding takes place with another repeat unit or another atom or molecule or group or moiety as appropriate with the structure of the group as shown.

As used herein, the terms “polymer composition” or “homopolymer composition” or “copolymer composition” are used herein interchangeably and are meant to include at least one synthesized polymer or copolymer, as well as residues from initiators, catalysts and other elements attendant to the synthesis of such polymer, where such residues are understood as not being covalently incorporated thereto. Such residues and other elements considered as part of the polymer composition are typically mixed or co-mingled with the polymer such that they tend to remain with the polymer when it is transferred between vessels or between solvent or dispersion media. A polymer composition can also include materials added after synthesis of the polymer to provide or modify specific properties to such composition.

It should further be noted that the terms “polymer composition” and polymer formulation” are used herein interchangeably and shall be construed as being the same.

The term “photodefinable” refers to the characteristic of a material or composition of materials, such as a polymer composition in accordance with embodiments of the present invention, to be formed into, in and of itself, a patterned layer or a structure. In alternate language, a “photodefinable layer” does not require the use of another material layer formed thereover, for example a photoresist layer, to form the aforementioned patterned layer or structure. It will be further understood that a polymer composition having such a characteristic be employed in a pattern forming scheme to form a patterned film/layer or structure. It will be noted that such a scheme incorporates an “imagewise exposure” of the photodefinable material or layer. Such imagewise exposure being taken to mean an exposure to actinic radiation of selected portions of the layer, where non-selected portions are protected from such exposure to actinic radiation.

The phrase “a material that photonically forms a catalyst” refers to a material that, when exposed to “actinic radiation” will break down, decompose, or in some other way alter its molecular composition to form a compound capable of initiating a crosslinking reaction in the polymer, where the term “actinic radiation” is meant to include any type of radiation capable of causing the aforementioned change in molecular composition. For example, any wavelength of ultraviolet or visible radiation regardless of the source of such radiation or radiation from an appropriate X-ray and electron beam source. Non-limiting examples of suitable materials that “photonically form catalyst” include photoacid generators and photobase generators such as are discussed in detail below. It should also be noted that generally “a material that photonically forms a catalyst” will also form a catalyst if heated to an appropriate temperature.

Some embodiments in accordance with the present invention provide polycarbonate polymers that encompass repeating units derived from at least one adamantane epoxide monomer represented by the following formula (I):

Where each occurrence of R₁ and R₂ independently of each other selected from the group consisting of hydrogen, methyl, ethyl, linear or branched (C₃-C₁₂)alkyl, (C₆-C₁₀)aryl, (C₆-C₁₀)aryl(C₁-C₁₂)alkyl, (C₅-C₁₀)heteroaryl and (C₅-C₁₀)heteroaryl(C₁-C₃)alkyl; or

R₁ and R₂ taken together with the carbon atom to which they are attached form a (C₃-C₁₂)cycloalkyl ring optionally containing one or more heteroatoms selected from nitrogen, oxygen, sulfur and the like; and

each occurrence of R₃ R₄ and R₅ independently of each other selected from the group consisting of hydrogen, methyl, ethyl, linear or branched (C₃-C₁₂)alkyl, (C₃-C₁₂)cycloalkyl, (C₆-C₁₂)bicycloalkyl, (C₇-C₁₄)tricycloalkyl, (C₁₀-C₁₄)tetracycloalkyl, (C₆-C₁₀)aryl, (C₆-C₁₀)aryl(C₁-C₁₂)alkyl, (C₅-C₁₀)heteroaryl, (C₅-C₁₀)heteroaryl(C₁-C₃)alkyl, (C₁-C₁₂)alkoxy, (C₃-C₁₂)cycloalkoxy, (C₆-C₁₂)bicycloalkoxy, (C₇-C₁₄)tricycloalkoxy, (C₁₀-C₁₄)tetracycloalkoxy, (C₆-C₁₀)aryloxy(C₁-C₃)alkyl, (C₅-C₁₀)heteroaryloxy(C₁-C₃)alkyl, (C₆-C₁₀)aryloxy, (C₅-C₁₀)heteroaryloxy, (C₁-C₆)acyloxy and halogen.

In some other embodiments the polycarbonate polymers of this invention encompass not only the repeat units derived from compounds of Formula (I) but also one or more of any other known epoxide monomers, including any of the epoxides represented by the following epoxide Formula (II):

Where each occurrence of R₆ and R₇ independently of each other selected from the group consisting of hydrogen, methyl, ethyl, linear or branched (C₃-C₁₂)alkyl, (C₃-C₁₂)cycloalkyl, (C₆-C₁₀)aryl, (C₆-C₁₀)aryl(C₁-C₁₂)alkyl and heteroaryl; or R₆ and R₇ taken together with the carbon atom to which they are attached form a (C₃-C₁₂)cycloalkyl ring optionally containing one or more heteroatoms selected from nitrogen, oxygen, sulfur and the like.

Monomers

Embodiments in accordance with the present invention are suitable for the preparation of polymers encompassing a wide range of “adamantane” repeating units. As a representative example of such a compound or a monomer is “adamantane-oxirane-type” monomer (IA) that is shown below:

However, any of the substituted adamantane epoxides encompassed by Formula (I) can be employed to prepare the polycarbonates of this invention. A few of the adamantane epoxides of formula (I) are known in the literature. For example, adamanrane epoxide of formula (IA) is available from commercial sources, Sigma Aldrich. Various known synthetic procedures, similar to the one used for the preparation of adamantane epoxide of formula (IA) can be used to prepare the compounds encompassed by formula (I).

In some embodiments in accordance with the present invention, the compound represented by formula (I) is defined by the following substituents: each occurrence of R₁, R₂, R₃, R₄ and R₅ independently represents hydrogen, methyl, ethyl, cyclohexyl, phenyl or fluorine.

A few of the representative compounds encompassed by compound of formula (I) of this invention without any limitation are listed below:

Again, as noted above, a few of the compounds of Formula (I), such as for example, compound of formula (IA) is known in the literature and others can be synthesized by any of the procedures known to one skilled in the art. Specifically, several of the starting materials used in the preparation of the compounds of this invention are known or are themselves commercially available. The compounds of this invention and several of the precursor compounds may also be prepared by methods used to prepare similar compounds as reported in the literature and as further described herein.

Typically, the compounds of formula (I) can be prepared by subjecting a precursor vinylic compound of formula (III) to suitable epoxidation conditions as summarized in Scheme I. For example, such epoxidation reactions can be carried out by reacting compound of formula (III) with any of the known peroxides or peracids, such as for example, m-chloroperbenzoic acid at suitable reaction temperature in an organic solvent.

Polymers

Embodiments in accordance with the present invention also provide a polymer comprising the repeat units of formula (IV), said repeat unit is derived from a compound of formula (I) and carbon dioxide:

wherein:

represents a position at which the bonding takes place with another repeat unit;

each occurrence of R₁ and R₂ independently of each other selected from the group consisting of hydrogen, methyl, ethyl, linear or branched (C₃-C₁₂)alkyl, (C₆-C₁₀)aryl, (C₆-C₁₀)aryl(C₁-C₁₂)alkyl, (C₅-C₁₀)heteroaryl and (C₅-C₁₀)heteroaryl(C₁-C₃)alkyl; or

R₁ and R₂ taken together with the carbon atom to which they are attached form a (C₃-C₁₂)cycloalkyl ring optionally containing one or more heteroatoms selected from nitrogen, oxygen, sulfur and the like; and

each occurrence of R₃ R₄ and R₅ independently of each other selected from the group consisting of hydrogen, methyl, ethyl, linear or branched (C₃-C₁₂)alkyl, (C₃-C₁₂)cycloalkyl, (C₆-C₁₂)bicycloalkyl, (C₇-C₁₄)tricycloalkyl, (C₁₀-C₁₄)tetracycloalkyl, (C₆-C₁₀)aryl, (C₆-C₁₀)aryl(C₁-C₁₂)alkyl, (C₅-C₁₀)heteroaryl, (C₅-C₁₀)heteroaryl(C₁-C₃)alkyl, (C₁-C₁₂)alkoxy, (C₃-C₁₂)cycloalkoxy, (C₆-C₁₂)bicycloalkoxy, (C₇-C₁₄)tricycloalkoxy, (C₁₀-C₁₄)tetracycloalkoxy, (C₆-C₁₀)aryloxy(C₁-C₃)alkyl, (C₅-C₁₀)heteroaryloxy(C₁-C₃)alkyl, (C₆-C₁₀)aryloxy, (C₅-C₁₀)heteroaryloxy, (C₁-C₆)acyloxy and halogen.

In some of the embodiments the polymer of formula (IV) can be defined by the following substituents: each occurrence of R₃, R₄ and R₅ independently represents hydrogen, methyl, ethyl or fluorine; and each occurrence of R₁ and R₂ independently represents hydrogen, methyl, ethyl or phenyl.

In yet another embodiment, the polymer of formula (IV) can contain a repeat unit which is derived from a compound or monomer selected from one or more of the following:

In yet another embodiment any of the compounds of formula (I) described above can also be used as monomers to make the polymers of formula (IV) of this invention.

In another embodiment of this invention the polycarbonate of this invention further includes repeat units of formula (V) formed from the reaction of carbon dioxide with one or more epoxide monomer of formula (II) in addition to the repeat units of formula (IV).

Representative examples of epoxides of formula (II), without any limitation, include the following:

2-methyloxirane;

2-ethyloxirane;

2-isopropyloxirane;

2-(tert-butyl)oxirane;

2-(tert-pentyl)oxirane;

2-cyclopentyloxirane;

2-cyclohexyloxirane;

2-cycloheptyloxirane;

2-cyclooctyloxirane;

1-oxaspiro[2.5]octane;

1-oxaspiro[2.7]decane; and

2-norbornaneoxirane.

The polycarbonate polymers of formula (IV) feature alternating repeat units derived from each unit of the compound of formula (I) reacted with a molecule of carbon dioxide. The polymers of formula (IV) formed according to this invention generally exhibit a weight average molecular weight (M_(w)) of at least about 1,000. In another embodiment, the polymer of formula (IV) of this invention has a M_(w) of at least about 10,000. In another embodiment, the polymer of formula (IV) of this invention has a M_(w) of at least about 50,000. In yet another embodiment, the polymer of formula (IV) has a M_(w) of at least about 100,000. Generally, the larger the M_(w), the better the mechanical properties and thus feature not only better film forming properties but also feature good mechanical properties. Thus in an embodiment of this invention the polymer of formula (IV) exhibits a weight average molecular weight of from about 1,000 to about 300,000. The weight average molecular weight (M_(w)) and the number average molecular weight (M_(n)) are generally determined by gel permeation chromatography (GPC) using polystyrene calibration standards. However, any of the other known methods can also be used to determine M_(w) and M_(n). From this the polydispersity index (PDI) of the polymer can also be determined (M_(w)/M_(n)). In some embodiments of this invention the polydispersity index of the polymers of formula (IV) of this invention generally is from about 1 to 5, in some other embodiments of this invention the polydispersity index of the polymers of formula (IV) of this invention generally is from about 1 to 3, and yet in some other embodiments of this invention the polydispersity index of the polymers of formula (IV) of this invention generally is from about 1 to 2.

As noted above, the polymer of formula (IV) exhibit better thermal properties than those of conventional polycarbonates, such as polypropylene carbonate (PPC). In some embodiments of this invention, the polymer of formula (IV) exhibits a glass transition temperature (T_(g)) of at least about 100° C. In another embodiment of this invention, the polymer of formula (IV) exhibits a T_(g) of at least about 130° C. In yet another embodiment of this invention, the polymer of formula (IV) exhibits a T_(g) of at least about 150° C.

In another embodiment the polycarbonate of this invention containing both the repeat units of formula (IV) and (V) exhibit tailored thermal properties. That is, any desirable thermal properties can be achieved by suitable incorporation of repeat units of formula (IV) and (V). Thus in one of the embodiments of this invention the polycarbonate of this invention is comprised of 1:99 to 99:1 molar ratio of the repeat units of formula (IV) and (V) respectively. In another embodiment of this invention, the molar ratios of repeat units (IV) and (V) are respectively from 20:80 to 80:20. In yet another embodiment of this invention, the molar ratios of repeat units (IV) and (V) are respectively from 40:60 to 60:40.

In another embodiment of this invention there is also provided a process for making a polymer of formula (IV). The process involves reacting a compound of formula (I) with carbon dioxide in the presence of a ligand-supported metal catalyst optionally in the presence of a suitable solvent. Any one of the compounds of formula (I) including the compounds which are known in the literature as described above can be used to prepare the polymers of formula (IV). A similar process can be employed to make the co-polycarbonates containing both repeat units of formula (IV) and (V) by employing the desirable amounts of monomers of formula (I) and (II).

As noted, any of the suitable solvents that would not only dissolve the ligand-supported metal catalyst but also would bring about the reaction of compound of formula (I) with carbon dioxide can be employed. Suitable solvents generally include non-oxophilic solvents such as halogenated solvents or hydrocarbon solvents and mixtures thereof. Representative examples of solvents include, without any limitation, dichloromethane, 1,2-dichloroethane, chloroform, carbon tetrachloride, and the like.

Any of the ligand-supported metal catalyst that can bring about the reaction of compound of formula (I) with carbon dioxide can be used to form the polymer of formula (IV). Typically, such ligand-supported metal catalyst can be made from any of the metals selected from the group consisting of chromium, manganese, iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum and zinc.

It has now been found that ligand-supported metal catalysts derived from cobalt are advantageously useful in the process of this invention. Such cobalt metal complex catalysts may be represented by formulae (VI) or (VII):

Wherein R is methyl, ethyl, linear or branched (C₃-C₁₂)alkyl, (C₃-C₁₂)cycloalkyl and (C₆-C₁₀)aryl; and wherein Y is halogen, acetate, trifluoroacetate, benzoate, tosylate, triflate, mesylate, nitrate, C₆F₅CO₂ and azide. In one embodiment of the process of this invention, such catalyst employed is a cobalt complex of formula (VI) wherein R is tert-butyl. In another embodiment of the process of this invention, such catalyst employed is a cobalt complex of formula (VII) wherein Y is chlorine.

Advantageously, it has further been found that various co-catalysts can also be employed in the process of this invention. Suitable examples of such co-catalysts include without any limitation pyridine, N,N-dimethylpyridin-4-amine (DMAP), 4-(pyrrolidin-1-yl)pyridine (4-PYP), 2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidine (DBN), 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine (DBU), 2,3,4,6,7,8-hexahydro-1H-pyrimido[1,2-a]pyrimidine (TBD), 1,1,1-triphenyl-N-(triphenylphosphoranylidene)-phosphoraniminium halide (PPNX), 1,1,1-triphenyl-N-(triphenylphosphoranylidene)-phosphoraniminium azide (PPNN3), tetraethylammonium acetate and tricyclohexylphosphine. The structures of some of these co-catalysts are provided below.

In one of the embodiments the co-catalyst employed is of the formula (VIII):

In another embodiment of this invention there is further provided a sacrificial polymer composition comprising: one or more polymer of formula (IV) (or a copolymer containing repeat units of formula (IV) and (V)) as described herein; one or more of a photoacid generator (PAG) or photobase generator (PBG) or mixtures thereof; and a solvent. In one of the embodiments the sacrificial polymer composition of this invention can further comprise a thermally activated acid generator (TAG). The sacrificial polymer composition embodiments according to the present invention can encompass a single polycarbonate polymer or two or more polycarbonate polymer embodiments according to the present invention.

In another embodiment, the sacrificial polymer composition comprises a polymer of formula (IV) as described herein; one or more of a thermally activated acid generator (TAG) or a thermally activated base generator (TBG) and a solvent.

For some embodiments according to the present invention, the sacrificial polymer composition can optionally further include one or more solvents. Solvent can be present in an amount of from, for example, 10 to 99 percent by weight, or 40 to 90 percent by weight, or 50 to 80 percent by weight, based on the total weight of the sacrificial polymer composition. Various solvents can be employed to form the sacrificial polymer compositions of this invention. Representative examples of such solvents without any limitation include the following: anisole, n-butyl acetate (BuOAc), dimethylacetamide (DMAc), cyclopentanone, cyclohexanone, gamma butyrolactone (GBL), propyleneglycol-monomethylether acetate (PGMEA) and mixtures thereof.

Photoacid generators used in the sacrificial composition embodiments according to the present invention, generate an acid, such as but not limited to a protonic acid, after exposure to actinic light, such as but not limited to ultraviolet light, and/or elevated temperature, such as but not limited to temperatures of at least 100° C. Thermal acid generators used in sacrificial composition embodiments according to the present invention, generate an acid, such as but not limited to a protonic acid, after exposure to elevated temperature, such as but not limited to, temperatures of at least 100° C. With some embodiments, the thermal acid generator is selected from thermal acid generators that are also photoactive, such as but not limited to photoacid generators. With some embodiments, the thermal acid generator is selected from thermal acid generators that are not photoactive, such as but not limited to thermal acid generators that are not photoacid generators.

Photoacid generators and thermal acid generators, that can be included in sacrificial polymer composition embodiments according to the present invention, generate one or more acids that result in depolymerization, such as but not limited to catalytic depolymerization, of the polycarbonate polymer embodiments according to the present invention. As used herein, the term “depolymerization” means the polycarbonate polymer is at least partially broken down into smaller units each having a molecular weight less than the molecular weight of the polycarbonate polymer prior to depolymerization. Such depolymerized units, generally having properties distinct from those of the polymers before depolymerization, include but are not limited to: the monomers from which the polymer was derived; polycarbonate oligomers; hydroxyl-terminated polycyclic carbonate oligomers; polycyclic carbonates; polycyclic ethers; cyclic carbonates; cyclic ethers; and/or gasses, such as but not limited to CO and/or CO₂.

Photoacid generators that can be included in the sacrificial composition can be selected from, for example, halonium salts and/or sulfonium salts. Examples of photoacid generators that can be included in sacrificial composition embodiments according to the present invention include, but are not limited to: 4-methylphenyl[4-(1-methylethyl)phenyl] iodonium tetrakis(pentafluorophenyl)borate; bis(4-tert-butylphenyl)iodonium triflate; di(4-tert-butyl)phenyliodonium bis(perfluoromethane-sulfonyl)imide; di(4-tert-butylphenyl)iodonium tris(perfluoromethanesulfonyl)methide; tris(4-tert-butylphenyl)sulfonium tetrakis(pentafluorophenyl)borate; tris(4-tert-butylphenyl)sulfonium hexafluorophosphate; triphenylsulfonium hexafluoroantimonate; triphenylsulfonium bis(perfluoromethanesulfonyl)imide; triphenylsulfonium tris(perfluoromethanesulfonyl)methide; tris[4-[(4-acetylphenyl)thio]phenyl]sulfonium tris((trifluoromethyl)sulfonyl)methanide (trade designation, GSID-26-1); tris[4-[(4-acetylphenyl)thio]phenyl]sulfonium tetrakis(pentafluorophenyl)borate (trade designation, IRGACURE® PAG 290); triphenylsulfonium tris[(trifluoromethyl)sulfonyl]methanide (trade designation, TPS-C1); triphenylsulfonium 4,4,5,5,6,6-hexafluorodihydro-4H-1,3,2-dithiazine-1,1,3,3-tetraoxide (trade designation, TPS-N3); and combinations of two or more thereof. GSID-26-1 and IRGACURE® PAG 290 are commercially available from BASF Corporation. TPS-C1 and TPS-N3 are commercially available from DayChem Laboratories, Inc.

Thermal acid generators that can be included in sacrificial polymer composition embodiments according to the present invention include, but are not limited to: thermal acid generators that include a cation selected from ammonium, pyridinium, halonium, such as but not limited to iodonium, and sulfonium, and a weakly coordinating anion; N-sulfoximides; and combinations of two or more thereof. Generally the acids from which the weakly coordinating anions are formed have a pKa of less than 2.0 while in some other embodiments the acid having a pKa of 0.75 or less and for still other embodiments the acid having a pKa of −0.5 or less are employed. Examples of weakly coordinating anions include anions of strong acids, which can have pKa values of less than or equal to −2, and which can include, but are not limited to: hexafluoroarsenate (AsF₆ ⁻); hexafluoroantimonate (SbF₆ ⁻); hexafluorophosphate (PF₆ ⁻); perfluoroalkyl sulfonates, such as, trifluoromethane sulfonate (CF₃SO₃ ⁻), perfluorobutyl sulfonate (C₄F₉SO₃ ⁻), and perfluorooctylsulfonate (C₈F₁₇SO₃ ⁻); bis(perfluoroalkylsulfonyl)imide anions, such as, bis(trifluormethylsulfonyl) imide anion, (CF₃SO₂)₂N⁻; tris(perfluoroalkylsulfonyl)-methides, such as, tris(trifluoromethylsulfonyl)methide, (CF₃—SO₂)₃C⁻; tetrakis-(pentafluorophenyl)borate, (C₆F₅)₄B⁻; tetrakis(3,5-perfluoroalkyl-phenyl)borates, such as, tetrakis(3,5-trifluoromethylphenyl)borate, (3,5-(CF₃)₂C₆H₃)₄B⁻; and combinations of two or more thereof.

Various aforementioned examples of PAGs, PBGs and TAGs are enumerated structurally below without any limitation or preferences:

Ammonium salts from which the thermal acid generator can be selected, can be represented by the following general formula TAG-1, R¹⁰R¹¹R¹²R¹³N⁺(A⁻)  TAG-1

With reference to formula TAG-1, R¹⁰R¹¹R¹²R¹³N⁺ represents an ammonium cation in which R¹⁰, R¹¹, R¹² and R¹³ are each independently selected from hydrogen and hydrocarbyl. In some embodiments no more than one of R¹⁰, R¹¹, R¹² and R¹³ is selected from hydrogen. In some embodiments, each of R¹⁰, R¹¹, R¹² and R¹³ are independently selected from hydrocarbyl, and none of R¹⁰, R¹¹, R¹² and R¹³ are hydrogen. The hydrocarbyls from which each R¹⁰, R¹¹, R¹² and R¹³ can be independently selected include those classes and examples as described above. The symbol A⁻ of formula TAG-1 represents a weakly coordinating anion, which can be selected from those classes and examples as described previously herein.

With further reference to formula TAG-1, at least one of R¹⁰, R¹¹, R¹² and R¹³ includes an ether group represented by —O—R¹⁴, where R¹⁴ is a hydrocarbyl group. For some embodiments, R¹⁰ and R¹¹ are each methyl (—CH₃), R¹² is phenyl (—C₆H₅) and R¹³ is 4-methoxybenzyl

Pyridinium salts from which the thermal acid generator can be selected, can be represented by the following general formula TAG-2,

With reference to formula TAG-2, (R¹⁵)_(z)C₅H_((5-z))N⁺ A⁻, represents a pyridinium cation, in which R¹⁵, if present, is independently selected for each z from hydrocarbyl, R¹⁶ is independently selected from hydrocarbyl or hydrogen, and z is from 0 to 5, such as 0, 1, 2, 3, 4 or 5. The hydrocarbyls from which each of R¹⁵ and R¹⁶ can be independently selected include those classes and examples as described previously herein. The symbol A⁻ of formula TAG-2 represents a weakly coordinating anion, which can be selected from those classes and examples as described previously herein.

N-sulfoximides from which the thermal acid generator can be selected include, but are not limited to, those represented by the following general formula TAG-3,

With reference to formula TAG-3, R¹⁷ is a hydrocarbyl linking group having at least two adjacent carbons, at least two adjacent carbons of R¹⁷ optionally having bonded thereto a fused ring selected from non-aromatic rings, polycyclic rings and aromatic rings, and R¹⁸ is selected from halohydrocarbyl and perhalocarbyl. Examples of N-sulfoximides from which the thermal acid generator can be selected include, but are not limited to, those represented by the following general formulae TAG-4 through TAG-8.

With reference to general formulae TAG-3 through TAG-8, R¹⁸ in each case independently represents a halohydrocarbyl group. In an embodiment, R¹⁸ of general formulae TAG-3 through TAG-8 independently represents a perhalocarbyl group, such as but not limited to perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, perfluoroheptyl and perfluorooctyl. In an embodiment, R¹⁸ of general formulae TAG-3 through TAG-8 is trifluoromethyl.

With reference to general formulae TAG-6 and TAG-7, Y in each case is independently selected from —CH₂—, —CH₂—CH₂— and —O—. For some embodiments, Y of general formulae TAG-6 and TAG-7 is in each case independently selected from —CH₂— and —O—.

Halonium and sulfonium cations from which the cations of the thermal acid generator can be selected include those known to one skilled in the art. Typically, halonium cations, such as but not limited to iodonium, are substituted with two aryl groups, such as but not limited to phenyl or substituted phenyl groups, such as but not limited to 4-tert-butylphenyl. Sulfonium cations are typically substituted with three aryl groups, such as but not limited to phenyl or substituted phenyl groups, such as but not limited to 4-tert-butylphenyl. Examples of halonium and sulfonium cations include, but are not limited to, those recited previously herein with regard to the photoacid generator, such as but not limited to bis(4-tert-butylphenyl)iodonium and triphenylsulfonium.

Sulfonium salts from which the thermal acid generator can be selected include, but are not limited to, those represented by the following general formula TAG-9.

With reference to general formula TAG-9, R¹⁹ can independently for each p be selected from a halo group, a hydrocarbyl group, or R²²—O—, where R²² is a hydrocarbyl group, and p is from 0 to 4, such as 0, 1, 2, 3 or 4. The groups R²⁰ and R²¹ of general formula TAG-9 can each be independently selected from hydrocarbyl, or can together form a ring, such as but not limited to a 5 or 6 membered ring. For example, R²⁰ and R²¹ can each be independently selected from methyl, ethyl, cyclopentyl, cyclohexyl and 2-norbornyl. The T group of general formula TAG-9 can be selected from —CH₂—, —C₂H₄— or —CH₂—O—. The symbol A⁻ of formula TAG-9 represents a weakly coordinating anion, which can be selected from those classes and examples as described previously herein.

The sacrificial polymer composition of this invention further comprises optional additives selected from the group consisting of sensitizer, adhesion promoters, antioxidants, antioxidant synergists and fillers.

Representative examples of such optional additives are selected from 1-chloro-4-propylthioxanthane (CPTX), isopropyl thioxanthone (ITX), phenothiazine, benzoquinone and 1,1,1-tris(hydroxymethyl)propane (THMP).

For some embodiments according to the present invention, the polycarbonate polymer can be present in the sacrificial polymer composition in an amount of from 1 to 99.5 percent by weight, or 1 to 75 percent by weight, or 1 to 60 percent by weight, based on the total weight of the sacrificial polymer composition. The balance of percent weights is made up by the carrier solvent, photoacid generator and/or thermal acid generator, and optional components including, but not limited to, optional antioxidant, optional antioxidant synergist, optional co-solvent, and/or optional fluxing agent, such as formic acid.

Generally, any desirable amounts of PAGs, PBGs or TAGs, as described herein can be employed with the sacrificial polymer composition of this invention. In one embodiment, the PAG or PBG loading is from about 0.15 parts per hundred polymer to 10 parts per hundred polymer, or from 0.75 parts per hundred polymer to 6 parts per hundred polymer, or from 1 parts per hundred polymer to 3 parts per hundred polymer.

For some embodiments according to the present invention, the sacrificial polymer composition can be a photodefinable sacrificial polymer composition which is generally a positive-tone material. The photodefinable sacrificial polymer composition is typically applied in the form of a coating over a substrate, such as, a silicon chip or wafer to form a layer or film thereon. Typically, after forming such layer, the composition is image-wise exposed to actinic radiation of an appropriate wavelength and energy. In the case of a positive tone photodefinable sacrificial polymer composition, those portions exposed to actinic light passing through the photomask are removed during a development step, including but not limited to solvent washing or thermal decomposition, and the unexposed portions are retained on the substrate.

The photomask can be a gray scale photomask. The gray scale photomask encodes an optical density profile into the underlying photodefinable sacrificial polymer composition, and thereby defines a three-dimensional photodefined structure therein. Actinic light passing through the gray scale photomask typically penetrates at variable depths into the underlying photodefinable sacrificial polymer composition, thereby resulting in the formation of three-dimensional structures in the subsequently developed coating.

The photosensitive composition embodiments of the present invention generally encompass a photoacid generator, as has been described previously herein. As discussed previously herein, upon exposure to actinic radiation of an appropriate wavelength and energy, the photoacid generator generates an acid that causes at least partial depolymerization of the sacrificial polycarbonate polymer. The result of such depolymerization being a lowering of the decomposition temperature of such exposed regions, while those portions that are not exposed are not depolymerized and retain the polymer's original decomposition temperature. Generally such depolymerization also increases the solubility of exposed regions, as compared to unexposed regions, thus allowing for a dissolution-based pattern development process to be employed.

As discussed previously herein with regard to polycarbonate polymer embodiments in accordance with the present invention, sacrificial polymer composition embodiments according to the present invention can be characterized with regard to the temperature at which the polymer depolymerizes or decomposes. This temperature can be referred to as a depolymerization temperature or a decomposition temperature of the sacrificial polymer. Such temperature can be quantified with regard to the T_(d50) decomposition temperatures, that is, temperature at which fifty weight percent (50 wt. %) of the polymer is decomposed.

In another embodiment, the sacrificial polymer composition of this invention features surprisingly unique thermal properties. In some embodiments of the polymer composition of this invention, it has now been observed that the difference between the thermal decomposition temperature (T_(d)) of the polymer in the composition after actinic radiation and the glass transition temperature of the polymer (T_(g)) is generally not greater than 30° C., that is (T_(d)−T_(g)<30° C.).

As previously described herein, polycarbonates, such as PPC will decompose when heated to temperatures above 225° C., with the 50% weight loss temperature (T_(d50)) around 250° C. typically observed in dynamic TGA (10° C./min). Not wishing to be bound by any theory, it is believed that such decomposition is initiated by thermal scission of the carbon-oxygen bond, the weakest bond in the polymer chain, followed by subsequent intramolecular ring closing which generates small cyclic molecules that are volatile and will escape from the film as gaseous species. This mode of decomposition in general requires an initiation temperature of at least >200° C., and offers limited opportunity to define a pattern unless the polycarbonate is used to fill the selected area already patterned by an alternative method.

It has been found that a catalytic amount of acid (H⁺) results in more efficient decomposition as described in Journal of Microelectromechanical Systems, 2003, 12(2), 147-159. As described therein a “catalytic” amount of an acid initiates chain scission of PPC followed by intramolecular “back-biting” to yield propylene carbonate, propylene oxide, acetone, and carbon dioxide as decomposition products. Irradiation of a formulation of the polycarbonate with a photoacid generator (PAG) is an efficient means of introducing the acid catalyst only in the exposed areas, thus providing a photodefinable patterning opportunity.

Alternatively, a base (:B in equation below, e.g., OH⁻, OR⁻, R₃N) could be used to initiate polymer chain scission and allow subsequent intramolecular formation of small cyclic molecules as shown in the equation below. Thus it has been our working hypothesis that selected photobase generators (PBG) will be equally effective as light-induced catalyst initiators in photodefinable applications.

While it has been generally believed that acid generators are photo-responsive, the bases released from base generators were relatively weak and in no way comparable to the superacid typically derived from the acid generators. The photobase generators PT-393 and PT-407M as described herein releases some of the strongest organic bases, e.g., TBD and MTBD, with pKa of their conjugated acids (as shown below)>20 in acetonitrile (J. Org. Chem. 2005, 70, 1019-1028).

We believe that these bases are strong enough to deliver comparable or even improved polymer decomposition performance as their acid counterparts and leave less residue after development because the catalyst-related species generated upon UV exposure are all considered small organic molecules.

From the examples that follows, it has now been surprisingly found that T_(g) of polycarbonate derived from adamantane epoxide was above 150° C. It is expected that the T_(d50) of this polycarbonate is lower than 200° C. A match of T_(g) with the T_(d) of the exposed material reduces issues due to thermal flow, and gives the best retention of pattern fidelity and image resolution possible. Our invention includes polycarbonates with high T_(g) that is adjustable by changing the rigid side chain derived from the epoxide monomer. Furthermore, the selection and loading of the photoactive additive can be optimized to give the best match of exposed T_(d) to the T_(g) of the material, thus delivering a photoimageable system with sufficient patterning resolution.

In further accordance with embodiments of the present invention, there is also provided a method of forming a structure. The structure forming method encompasses forming a three-dimensional structure on a surface of a substrate, where the three-dimensional structure typically includes a sacrificial polymer composition as described above. An overcoat layer is applied over the three-dimensional structure where such overcoat layer is essentially transparent to the appropriate wavelength of radiation that can activate the photoacid generator, the exposure to such light can be used to activate such acid generator. At the same time, as many photoacid generators are also thermally activated, generally the substrate having the aforementioned three-dimensional structures can also be heated to an elevated temperature sufficient to cause depolymerization of the sacrificial polymer and decomposition and vaporization of the products of such depolymerization. Such a process results in the forming of a three-dimensional space interposed between the overcoat layer and the substrate wherever a three-dimensional structure of such sacrificial polymer had resided. Such space is the result of the conversion of the at least partially depolymerized polymer and its depolymerization products into gaseous components that permeate through the overcoat layer. Where such overcoat layer is essentially opaque, the aforementioned three-dimensional structures are not exposed to a light source and are decomposed directly by heating to an appropriate elevated temperature. The elevated temperature being less than a decomposition temperature of the overcoat layer and substrate.

The three-dimensional structures and the corresponding three-dimensional spaces can each independently have any suitable dimensions, such as heights, lengths and/or widths. The three-dimensional structures and the corresponding three-dimensional spaces can each independently have: a height of from 0.01 to 200 micrometers; a width of from 0.01 to 10,000 micrometers; and a length of from 0.01 micrometers to 100 meters. A plurality of three-dimensional structures/three-dimensional spaces, such as but not limited to a plurality of interconnected three-dimensional structures/three-dimensional spaces, can be formed in methods according to embodiments of the present invention, so as to result in larger and/or more intricate three-dimensional structures/three-dimensional spaces, which can include multiple bends and/or curves in the x-, y-, and/or z-planes.

The overcoat layer can have any suitable thickness, provided it possesses the property of allowing any decomposition products of the sacrificial polymer to permeate therethrough. Typically, the overcoat layer has a thickness of from 1 to 500 micrometers, or from 2 to 300 micrometers, or from 5 to 100 micrometers.

In some sacrificial polymer composition embodiments in accordance with the present invention both a photoacid generator and a thermal acid generator are present. For such embodiments the thermal acid generator is provided to ensure decomposition of three-dimensional structures formed from such sacrificial polymer compositions upon heating to an effective elevated temperature, without the need for an exposure step after such structures are over-coated. Such elevated temperature being from 50° C. to 400° C. for some embodiments, from 80° C. to 250° C. for some other embodiments and from 70° C. to 150° C. for still other embodiments.

In accordance with further embodiments of the present invention, there is provided a method of temporarily bonding a first substrate and a second substrate together. The temporary bonding method encompasses forming a multilayered structure that includes the first substrate, the second substrate, and a temporary bonding layer interposed between the first substrate and the second substrate and applying an effective amount of pressure and/or heat to fixably couple the first substrate to the second substrate. The temporary bonding layer includes a sacrificial polymer composition embodiments of the present invention, as described above. Such temporary bonding layer can alternatively be referred to as a temporary adhesive layer.

To decouple or separate the first and second substrates after fixably coupling such substrates, the acid generator of the sacrificial polymer composition is activated, thereby generating an acid which, at least partially depolymerizes the polycarbonate polymer resulting in the lowering of the polymer's molecular weight, thereby at least partially degrading the temporary bonding layer. As a result of this degrading of the bonding layer, the substrates can be effectively separated from one another via any appropriate and effective process, for example, by a slide-off or wedge-off debonding process. While such decoupling generally leaves residue of the bonding layer on one or both substrates, advantageously the depolymerized polymer residues are readily removed by one or both of (1) heating the substrates to an elevated temperature sufficient to forming gaseous products of the decomposition of such depolymerized polymer residue and (2) rinsing such substrates with appropriate aqueous and/or organic solvents. As before, the elevated temperature at which such depolymerization is conducted, is less than a decomposition temperature of the first substrate and less than a decomposition temperature of the second substrate.

The temporary bonding layer can be applied in the form of a coating or film to a surface either one or both substrates prior to bringing the substrates together to sandwich the bonding layer and form the multilayered structure. The temporary bonding layer can be applied to such surface(s) using any appropriate coating method, including, but not limited to those described previously herein. The first and second substrates, with the temporary bonding layer interposed there-between can be subjected to any appropriate process (e.g. wafer thinning or planarization) as a multilayered structure and then subsequently debonded by either the aforementioned wedge-off or slide-off processes.

Sacrificial polymer composition embodiments in accordance with the present invention can optionally include a crosslinking agent that is thermally and/or photonically activated. The crosslinking agent forms a three-dimensional crosslink network within the sacrificial polymer composition that can result in an increased polymer decomposition temperature. Such cross-linked polymers are then useful for the fabrication of various microelectronic devices where such an increased decomposition temperature is advantageous (e.g. MEMS devices).

The first and second substrates can each be independently selected from any suitable materials, such as, but not limited to: metals, such as but not limited to copper, aluminum, steel, and metal alloys; inorganic materials, such as but not limited to silicon dioxide, silicon nitride, and aluminum oxide; organic materials, such as but not limited to organic polymers, such as but not limited to crosslinked organic polymer compositions; and combinations of two or more thereof. While temporarily bonded to each other, the first and/or second substrates are typically modified by methods including, but not limited to, machining, such as but not limited to, chemical mechanical polishing or planarization. In particular, the first surface of the first substrate and/or the second surface of the second substrate are modified. For some embodiments, the second substrate is a die, and the first substrate is a semiconductor wafer. If the semiconductor wafer/first substrate is subjected to a wafer thinning process, the active surface of the semiconductor wafer corresponds to the second surface of the first substrate, and is in facing opposition to the first surface of the second substrate. If the semiconductor wafer/first substrate is subjected to a wafer planarization process, the active surface of the semiconductor wafer corresponds to the first surface of the first substrate, and accordingly faces away from the second substrate.

The sacrificial polymer compositions, polycarbonate polymers and methods in accordance with embodiments of the present invention can be used in or in conjunction with numerous applications including, but not limited to: microelectronics, such as but not limited to microprocessor chips, communication chips, and optoelectronic chips; microfluidics; sensors; and analytical devices, such as but not limited to microchromatographic devices.

It is common practice to use photoacid generators to generate a superacid (H⁺), such as H-FABA because the PAG is regarded as being more efficient in generating an acid and can be activated at 365 nm. The strength of the superacid generated enables the spontaneous decomposition of PPC at moderate to high temperatures. One disadvantage is that these PAG contain halogens and heavy metals.

In contrast it is generally accepted that photobase generators have much lower quantum efficiency and also require shorter wavelength (248 nm) for activation. Our photobase generators, such as PT-393 and PT-407M, generate very strong bases (pK_(a)>20 in acetonitrile) and are capable of decomposing PPC at temperatures lower than those compositions that contain PAGs. Advantageously, the PBG of this invention do not contain heavy atoms or groups (e.g., iodine, antimony, borate) that have been known to leave residues unremovable by heat alone. PBGs are included in some of our compositions with the understanding that base generators give cleaner thermal decomposition than halogen-containing acid generators.

There are several advantages foreseen by the practice of the present invention. As a non-limiting example the polymer compositions/formulations provide potentially better image resolution material with good retention of pattern fidelity by reducing thermal flow issues during thermal development due to low T_(g) of PPC. The family of higher T_(g) polycarbonates in this invention is clearly modular, and the rigid structure of the polymer backbone can be changed by adjusting the substituted epoxide monomer. This in turn allows proper tailoring of the polymer to fit formulation and application requirements, e.g., dissolution in a specific process solvent and miscibility with selected photoactive additives. The photoactive component, and its loading, in the compositions can also be adjusted. With a proper selection of the photoactive additive to interact with the specific high T_(g) polycarbonate, a low-temperature post-exposure development can be achieved to yield high resolution patterns with little to no residue.

Prior solutions addressed residue concerns by identifying the root causes as decomposition products of the photoacid generators, namely iodine from the iodonium salts or metal species from antimony-containing anions, although a true resolution remains to be found. None of the photoactive additives in this invention contains heavy metal ions. Furthermore, the photobase generators PT-393 and PT-407M are not simple substitutes of existing photoacid generators. Unlike traditional PAGs which rely on the iodonium cations or fluorinated anions to generate a superacid, these photobase generators contain only carbon, hydrogen, nitrogen, and oxygen. Here the bases released are sufficiently strong to initiate base-catalyzed polycarbonate decomposition. This is a sharp contrast to the class of non-halogenated PAGs, which are generally ineffective in initiating polymer decomposition. Thus, the introduction of this class of photobase generators as the photo package addresses a long-standing desire of the semiconductor industry to remove halogenated components from patternable packaging or device fabrication materials.

This invention is further illustrated by the following examples which are provided for illustration purposes and in no way limit the scope of the present invention.

EXAMPLES

The following examples describe the procedures used for the preparation of various starting materials employed in the preparation of the compounds of this invention.

Alternating copolymerization of carbon dioxide (CO₂) and 1-adamantyl oxirane (AdEO) was carried out using tetraphenylporphyrinatocobalt(III) chloride ((TPP)CoCl) as a catalyst and 4-(dimethylamino)pyridine (DMAP) as a co-catalyst. TPPCoCl was prepared following the procedure reported in the literature, see for example, Sugimoto, H.; Kuroda, K. The Cobalt Porphyrin-Lewis Base System: A Highly Selective Catalyst for Alternating Copolymerization of CO₂ and Epoxide under Mild Conditions Macromolecules 2008, 41, 312-317.

Analytical Methods

¹H-NMR spectra were obtained in deuterated chloroform (CDCl₃) with tetramethylsilane (0.0 ppm) as an internal standard at 30° C. using a Bruker-DPX400 (400 MHz) spectrometer. The Infrared (IR) spectra were recorded with a JASCO spectrometer FT/IR-4100 for the polymer cast film from CHCl₃ solution on NaCl plate. The gel permeation chromatography (GPC) was performed at 40° C. on a Tosoh model HLC-8220 high-speed liquid chromatography equipped with two TSKgel SuperMultiporeHZ-H columns, a differential refractive index (RI) detector with THF as an eluent at a flow rate of 0.35 mL min⁻¹. The molecular weight calibration curve was obtained with standard polystyrenes (TSK standard polystyrene from Tosoh Co.). The differential scanning calorimetric (DSC) measurements were performed using a Mettler-Toledo DSC 3-analyzer at a heating and cooling rate of 10° C. min⁻¹. The reported T_(g) values were determined from the second heating scan.

Example 1

1-Adamantyloxirane (AdEO) was prepared using the following procedure.

3-Chloroperbenzoic acid (mCPBA) (344 g, 1.51 mol, 1.51 equivalents, <77%) was placed into a 4-neck 5 L flask fitted with mechanical stirrer, thermowell, nitrogen inlet, and addition funnel. Dichloromethane (2000 ml) was added and the mixture stirred. Some, but not all mCPBA dissolved. The mixture was chilled to 2.5° C. with a methanol-ice bath. 1-Vinyladamantane, purchased from DayChem Laboratories, Inc., (164.5 g, 1.015 mol) was added dropwise over 27 minutes with the temperature ranging from 2.5 to −7.8° C. When the temperature reached −5° C., the methanol-ice bath was drained and replaced with ice-water. The reaction mixture was stirred for two hours at −0.4 to 5° C. A mild exotherm occurred within the first hour. The ice bath was removed and the reaction mixture was allowed to warm to room temperature. The mixture was allowed to stir overnight, GC analysis showed no vinyladamantane. The reaction mixture tested positive with KI/starch paper. Four hundred fifty ml of 10% aqueous sodium bisulfite solution were added. The quench was exothermic, causing the temperature to rise to −38° C. and resulting in some unexpected boil out of the dichloromethane. The KI/starch paper test was now negative. The reaction mixture was filtered. Solids precipitated in the filtrate so the filtrate was filtered through filter cake. The filter cake was washed generously with dichloromethane. Clear phases separated in the filtrate. The upper aqueous phase had pH=2. The dichloromethane phase was stirred as three portions of 100 ml saturated sodium bicarbonate solution were added cautiously. The mixture was then treated cautiously with 55 g, 79 g, and 58 g portions of solid sodium bicarbonate until the effervescence ceased. The aqueous phase had pH=8-9. The organic phase contained copious white solids, so was treated with 300 ml water. The phases were separated and the dichloromethane phase decanted away from the remaining solids. The solids were treated with 200 ml water and then returned to the organic phase. The phases were separated. Aqueous phase pH was 8. The solids in the interface were filtered and resulting phases separated. The organic phases were combined, dried over sodium sulfate until clear, filtered, and rotary evaporated to 179.6 g clear, nearly colorless liquid for 99% yield. GC analysis showed 99.1% adamantyl oxirane. Adamantyl oxirane can be distilled by vacuum distillation for further purification (85° C./3.5 Torr).

Example 2

The polymerization was conducted with no solvent at the beginning. Dichloromethane was added after the reaction mixture solidified.

A magnetic stirring bar, (TPP)CoCl (0.05 mmol) and DMAP (0.0375 mmol) were placed in an appropriately sized stainless autoclave and the autoclave was sealed under nitrogen atmosphere. AdEO (25 mmol) and methylene chloride (3 mL) were added to the autoclave via glass syringe, and then CO₂ was pressurized into the autoclave at 5 MPa and the mixture was stirred at 40° C. Small amount samples were taken out by a syringe and needle after depressurizing the autoclave for monomer conversion and molecular weight measurement. The reaction was stopped by releasing CO₂ at day 10, and chloroform (25 mL) was added to the reaction mixture, then the solution was added into methanol to stop the polymerization and to collect the produced polymer as precipitates. After dried in vacuo, a small portion of the polymer was subjected to ¹H NMR and IR analyses for determining the polymer structure, to GPC for estimating the number-average molecular weight (M_(n)), weight-average molecular weight (Ma) and molecular weight distribution (M_(w)/M_(n)), and to DSC for determining the glass transition temperature (T_(g)). (75% conversion, M_(n)=9,600, degree of polymerization (DP)=43).

Comparative Examples 1-4

The procedures of Example 1 were substantially repeated in these Comparative Examples 2-4 except for using various different epoxides as summarized in Table 1 to make the corresponding polycarbonates. Also summarized in Table 1 are the time required for the polymerization, conversion, M_(n), (M_(w)/M_(n)) and DP.

TABLE 1 Time Conv. T_(g) Ex. No. Epoxide Polymer (days) (%) M_(n) M_(w)/M_(n) DP (° C.) 1 AdEO PAdEC 10 75 9,600 1.39 43 158 Comp. 1 PO PPC 2 74 18,800 1.21 184 30 Comp. 2 CyEO PCyEC 5 72 26,400 1.24 155 55 Comp. 3 ^(t)BuEO P^(t)BuEC 15 69 32,800 1.17 228 70 Comp. 4 NBEO PNBEC 5 78 25,900 1.2 142 85 PO - propylene oxide (2-methyloxirane); CyEO - 2-cyclohexyloxirane; ^(t)BuEO - 2-(tert-butyl)oxirane; NBEO - 2-norbornaneoxirane; PAdEC - polyadamantylethylene carbonate; PPC - polypropylene carbonate; PCyEC-polycyclohexylethylene carbonate; P^(t)BuEC - poly^(t)butylethylene carbonate; NBEO - poly-2-norbornylethylene carbonate.

FIG. 1 shows the DSC thermograms of the polycarbonates obtained in Example 1, which is compared with those of the polycarbonates of Comparative Examples 1-4. It is surprising that the T_(g) of the polyadamantylethylene carbonate (PAdEC) of Example 1 is the highest T_(g) ever measured for a polycarbonate.

Although the invention has been illustrated by certain of the preceding examples, it is not to be construed as being limited thereby; but rather, the invention encompasses the generic area as hereinbefore disclosed. Various modifications and embodiments can be made without departing from the spirit and scope thereof. 

What is claimed is:
 1. A polymer consisting of a repeat unit of formula (IV), said repeat unit is derived from a compound of formula (I) and carbon dioxide:

wherein:

represents a position at which the bonding takes place with another repeat unit; each occurrence of R₁ and R₂ independently of each other selected from the group consisting of hydrogen, methyl, ethyl and phenyl; and each occurrence of R₃ R₄ and R₅ independently of each other selected from the group consisting of hydrogen, methyl, ethyl and halogen.
 2. The polymer according to claim 1, wherein: each occurrence of R₁ and R₂ independently represents hydrogen, methyl, ethyl or phenyl; and each occurrence of R₃, R₄ and R₅ independently represents hydrogen, methyl, ethyl or fluorine.
 3. The polymer according to claim 1, wherein said repeat unit of formula (IV) is derived from a compound selected from one or more of the following:


4. The polymer according to claim 1, wherein the weight average molecular weight of said polymer is from about 1,000 to about 300,000.
 5. The polymer according to claim 1, wherein said polymer exhibits a glass transition temperature of at least about 100° C.
 6. A process for making a polymer of formula (IV) according to claim 1 comprising: reacting a compound of formula (I) with carbon dioxide in the presence of a ligand-supported metal catalyst:

wherein:

represents a position at which the bonding takes place with another repeat unit; each occurrence of R₁ and R₂ independently of each other selected from the group consisting of hydrogen, methyl, ethyl and phenyl; and each occurrence of R₃ R₄ and R₅ independently of each other selected from the group consisting of hydrogen, methyl, ethyl and halogen.
 7. The process according to claim 6 which includes a halogenated solvent.
 8. The process according to claim 6, wherein the ligand-supported metal catalyst is selected from the group consisting of chromium, manganese, iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum and zinc.
 9. The process according to claim 6, wherein the catalyst is a cobalt metal complex of formulae (VI) or (VII):

wherein R is methyl, ethyl, linear or branched C₃-C₁₂-alkyl, C₃-C₁₂-cycloalkyl and C₆-C₁₀-aryl; and Y is halogen, acetate, trifluoroacetate, benzoate, tosylate, triflate, mesylate, C₆F₅CO₂ and azide.
 10. The process according to claim 9, wherein R is tert-butyl and Y is chlorine.
 11. The process according to claim 6, wherein it further comprises a co-catalyst, which is N,N-dimethylpyridin-4-amine.
 12. A sacrificial polymer composition comprising: a polymer according to claim 1; a photoacid generator (PAG) or photobase generator (PBG) or mixtures thereof; and a solvent.
 13. The sacrificial polymer composition according to claim 12, which further comprises a thermally activated acid generator (TAG).
 14. The sacrificial polymer composition of claim 12 where the solvent is selected from anisole, n-butyl acetate (BuOAc), dimethylacetamide (DMAc), cyclopentanone, cyclohexanone, gamma butyrolactone (GBL), propyleneglycol-monomethylether acetate (PGMEA) and mixtures thereof.
 15. The sacrificial polymer composition of claim 12 where the photoacid or photobase generator is selected from the following:

and mixtures in any combination thereof.
 16. The sacrificial polymer composition of claim 12, which further comprises optional additives selected from the group consisting of sensitizers, adhesion promoters, antioxidants, antioxidant synergists and fillers.
 17. The sacrificial polymer composition of claim 16, where said optional additives are selected from 1-chloro-4-propylthioxanthane (CPTX), isopropyl thioxanthone (ITX), phenothiazine, benzoquinone and 1,1,1-tris(hydroxymethyl)propane (THMP).
 18. The sacrificial polymer composition of claim 12 where the photoacid generator (PAG) or photobase generator loading is from 0.15 parts per hundred polymer to 10 parts per hundred polymer, inclusive.
 19. A polymer consisting of a repeat unit of formula (PAdEC), said repeat unit is derived from 2-(adamantan-1-yl)oxirane and carbon dioxide:


20. A sacrificial polymer composition comprising: a polymer according to claim 19; a photoacid generator (PAG) or photobase generator (PBG) or mixtures thereof; and a solvent. 